Helicopter antitorque and steering control



Sept. 23, 1947. .1. c., TROTTER HELICOPTER ANTITORQUE AND STEERING CONTROLS Filed June 19, 1947 2 Sheets-Sheet l INVENTOR I Jab/7 C. Fez/tar ATTORNEYS Q \N w g l MNQWH mm W N\ Sept, 23, 1947. J. c. TROLI'TER 2,427,982

HELICOPTER ANTITORQUE AND STEERING CONT ROLS File d June 19, 1947 2 Sheets-Sheet 2 INVENTOR Job/7 C Fowler ATTORNEYS Patented Sept. 23, 1947 ooN'rRoL John C. Trotter, South Burlington, Vt., assignor to Bell Aircraft Corporation, Wheatfield, N. Y.

Application June 19, 1947', Serial No. 755,602

7 Claims. (cram-17) This invention relates to helicopter aircraft, and more particularly to. flight control means therefor: and this application is a continuationimpart of my co-pending application Serial No. 542,637, filed June 29, 1944.

It is presently known to be desirable-to provide helicopter aircraft with lift rotor blade pitch change means and rotor-torque countering or directional control devices such as a laterally directed propeller at the tail of the fuselage. It is desirable to arrange the controls for the thrust output of the laterally directed propeller and the lift rotor blade pitch change device and the engine throttle so as to cause the counter-torque effects of the directional control deviceto be automatically adjusted approximately to match variations of the rotor torque reactions. I have determined that the use of mechanical linkage. means for such purposes invariably introduces mechanical complications and instabilizing lost motion and vibration producing effects. Also, such arrangements are inadequate to provide optimum directional control and stabilizing effects for utmost ease and facility of helicopter aircraft operation; and it is a primary object of the present invention to provide improved means for controlling the counter-torque airscrew and lift rotor control mechanisms in helicopter aircraft or the like whereby to provide improved performance and to eliminate difficulties and disadvantages of prior helicopter control arrangements.

Another object of the invention is to provide an automatic control system for the purpose referred to which is extremely light-weight; highly efficient in operation; simple to install and service; highly responsive to pilot-applied control actions; and which enables mechanical simplification of the entire aircraft to be accomplished because of elimination of the need of certain accessories such as starting clutch devices or the like. Other objects and advantages of the invention will appear from the specification herein after.

In the drawings:

Fig. 1 is a diagrammatic illustration of a heli- Copter power and control arrangement of the inv'ent'ion;

Fig. 2 is a vertical sectional view, on an enlarged scale, through a control mechanism for the pump supplying driving power to the tail propeller; and

Fig. 3 is a vertical section through the tail pro-j pelle'r power supply motor thereof. 1

The invention is illustrated in the drawing as applied to-a helicopter aircraft having the-usual type primary power. supply engine l0 and a lift rotor 12. The lift-rotor is shown mounted by means of a vertical. shaft 14 into driving connection with theengine 10. A tail propeller l5 h is indicated inFigs. 1-3. as being mounted upon the aircraft fuselage by means of a shaft 16 carried by bearings. l8 upon a housing structure 20whichlb0lts upon the aircraft fuselage in such manner as to mount the propeller 15 to be directedlaterally of the aircraft fuselage. Thus, rotation of the propeller Iii-will provide thrust forces in directions laterally of the aircraft forea-nd-aftcenter line, such as will counter the torque reaction-forces of the lift rotor I2 which. tend to drive the aircraft fuselage to rotate about the axisof the'rotor shaft M oppositely to the direction of rotor rotation.

. To supply power to the tailpropeller i5 I providea hydraulic'pressure supply pump device as. indicated-generally at 25 to be driven by means of a mechanical connection to the engine It). The pump 25'm'aybe of any suitable variable displace ment closed-circuit type, and by way of example the pump may-be of'the kind described and shown. in detail in U. SjRatent No. 2,190,812.

Conduits-SIF-G-Z" lead from the inlet and outlet portsof the pump 25 to provide a return-circuit fluid system leading from the pump 25 to the motor'for driving the tail propeller l 5, which motor will be described in detail hereinafter.

The power output of the pump 25 will of course vary with the engine speed, but to provide for. further con'trolof' the pump independently of. the speed thereof it is arranged to vary the rate; of fluid displacement thereof by rotating a control shaft of the pump; the control shaft being: furnished in a form such as the shaft I03 as; shown in U. SL P-atent No. 2,190,812. In applicantsJdraWing .(Fig. 2) the pump control stem is indicated atBSan'd is mounted by meansof a bearingfifi It'oextend from the pump housing 25. Asi shown in. Figs. 1-2 the control stem is arranged to, be controlled by a differential device 66 connected to the engine throttle lever 10 and to the, aircraft directional control device 12. As shown in Fig. 1 the connections to the throttle comprise .a push-pull member 14; a bell crank device 15; and. a link 16, whereby the throttle control'lever 10. is connectedto the engine throttle arm 17. The crank l 5- .alsoconnects through a link 18 to an arm '19 which extends from oneringgear'all of thefjdifierent'ial; while the direction'al controlfleyer "is coupled through a link til; .albell crank 82;, and a link 83 to an armill l' which extends-frorna"sleeve 85 carried'rotatably on the shaft 65. The sleeve mounts a pin 86 which carries the planetary gear 88 of the differential. The other ring gear 89 of the difi'erential is keyed to the shaft 65 as indicated at 90.

The lift rotor pitch mechanism is indicated at 92 in Fig. 1, and is connected through link 94 and bell crank 96 to the throttle control rod 14. As illustrated in Figs. 1 and 3, the power supply motor for the tail propeller I5 is indicated generally at I00. The control mechanism will be preferably so arranged that every pilot actuation of the lever 10 will produce an adjustment of the rotor pitch change mechanism and a simultaneous adjustment of the throttle so as to regulate the engine fuel supply in such manner that the rotor-engine unit will always operate at a substantially constant speed of revolution. Consequently, under increased pitch and correspondingly opened throttle conditions, the rotor will develop substantially greater torque than when operating under reduced pitch and reduced throttle conditions, although the engine speed will be substantially constant throughout the range of rotor torque reaction variances. Since the tail propeller I5 is powered by the hydraulic pumpmotor unit 25-400, of which the pump member is directly coupled to the engine I0, the thrust output of the propeller I5 will be constant except as the pump control .stem 65 is adjusted by operation of the difierential device 06 whichis in turn controlled byothe pilot levers 'I012.

For example, whenever the pilot lever 10 is .adjusted to change the lift rotor blade pitch an- ;gle (for vertical flight control purposes) the engine throttle will be automatically adjusted simul- :taneously therewith to ,maintain substantially constant rotor-engine speed under all normal op-- :in turn causes the pump control shaft 65 to bev rotated. The differential and control devices are arranged so as to change the tail propeller speed.

of rotation and the resultant thrust thereof in such manner as to substantially balance changes in the liftrrotor torque reaction. However, the

pilot may at any time override the automatic,

control influences affecting the tail propeller thrust output byadjusting the lever I2. There--v fore, although the automatic control differential mechanism is designed to provide accurately balancing control effects in respect to every pilot adjustment of the single control lever I0, the lever I2 may be pilot-manipulated at any time in order to provide for minor corrections in the directional control efiects as well as for changing the flight course; I V

, The tail propeller motor I is illustrated to include a housing I02 rotatably supporting a drive shaft I04. The shaft I04 carries a pinion I05 which meshes with agear I06 carried by the propeller shaft I6, whereby rotationof the motor shaft I04 will drive'the tail propeller IS. The motor device I00 maycomprise, generally speaking, a device similar to thepump 25 which is adapted for reverse operation; that is, to be driven in response to circulationlof pressured fluid thereinto from the conduits 80 02. For. example, the motor I00 may comprise afplurality of pistons IIO arranged to bedriven in sequence to reciprocate in such manner as to. cause a wobble plate device I20 to oscillate so, as to drive through means of a bearing I22a cam faced knob portion I25 of the shaftI04,Iwhereby1 theshaft I04 is These units are disposed respectively in direct connection with the primary engine In and the propeller I5, and are interconnected simply by means of closed conduits 60-62. Hence, the usual mechanically complicated and cumbersome and otherwise undesirable torque shaft, bevel gear boxes, drive chains, or the like, which have heretofore been necessarily employed to extend between the engine and the driven propeller are eliminated. It will also be appreciated that the power transmission and control arrangement of the invention effects substantial savings in weight; is easy to install and service; provides improved responsiveness to control motions; and eliminates the need for starting clutches or the like.

Although only one form of the invention has been shown and described in detail it will be apparent to those skilled in the art that the invention is not so limited but that various changes may be made therein without departing from the spirit of the invention or the scope of the appended claims. I g, a

What is claimed is:

1. In a helicopter aircraft, in combination a lift rotor, at power supply engine driving said lift rotor, a power output control for said engina a directional control propeller carried by said aircraft and directed laterally thereof to provide thrust forces countering the torque reaction forces transmitted to the aircraft fromthe lift rotor, and a hydraulic power supply system for said propeller comprising a pump devicedr iven by said engine and adapted to circulate pressured fluid through a closed circuit conduit system, said conduit system having a motor device in series therewith coupled to said propellerand adapted to operate in response to flow of pressuredfluid through said conduit system to drive said pro? peller, a fluid displacement control ,valve for said pump device, and a differentialigea'rinterconnecting said engine power output control and said fluid displacement control valve. .7

2. In a helicopter aircraft, in combinatioma lift rotor, a power supply engine driving said lift rotor, an engine throttle control device a directicnal control propeller carried by said (aircraft and directed laterally thereof to provide, thrust forces countering the torque reaction forces transmitted to the aircraft from the lift rotor, aj hy-j draulic power supply system for saidprop'eller comprising a variable displacementpump driven. by said engine and adapted to circulate pressure fluid through a closed circuit conduit system; s ai d conduit system having a motor in series there-" with and coupled to said propeller forjdrivingit'he latter in response to, flow of pressured fluid through said conduit system, a pumpdisplac ment control member, a differentialgearf having its driven element c'onnected'to. said pump control member for adjusting"the latter; said engine throttle being coupled to one-driving; element of said gear, and a pilot-o peraljrle direc tional control member coupled tothe other drive ing element of said gear. ;p

3. Ina helicopter air-craft, in combination wa:

lift rotor, a power supply engine driving said lift rotor, a power output control for said engine, a directional control propeller carried by said aircraft and directed laterally thereof to provide thrust forces countering the torque reaction forces transmitted to the aircraft from the lift rotor, a hydraulic power supply system for said propeller comprising a pump driven by said engine and adapted to circulate pressured fluid through a closed circuit conduit system, said con duit system having a motor in series therewith coupled to said propeller and adapted to operate in response to flow of pressured fluid through said conduit system to drive said propeller, a pump displacement control member, a differential gear having its driven element connected to said pump displacement control member and its driving elements connected respectively to said engine control and to a pilot-operable aircraft directional control member.

4. In an aircraft, in combination, a first rotor, an engine driving said rotor, an engine throttle control device, a second rotor carried by said aircraft and directed to provide thrust forces countering the torque reaction forces transmitted to the aircraft from said first rotor, a power supply system for said propeller comprising a constantly pressured variable displacement pump driven by said engine, a closed circuit fluid conduit system having a fluid pressure motor in series therewith and coupled to said second rotor for driving the latter in response to flow of pressure fluid through said conduit system, a pump displacement rate control member, a differential device having its driven'element connected to said pump control member for adjusting the latter, said engine throttle control being coupled to one driving element of said differential, and a pilot-operabledirectional control member coupled to the other driving element of said differential.

5. In a helicopter aircraft, in combination, a lift rotor, an engine driving said lift rotor, a lift rotor thrust control device, a directional control propeller carried by said aircraft and directed laterally thereof to provide thrust forces countering the torque reaction forces transmitted to the aircraft from the lift rotor, a hydraulic power supply system for controlling the thrust of said propeller comprising a variable displacement pump driven by said engine and adapted to circulate pressured fluid through a closed circuit conduit system, said conduit system having a motor in series therewith and coupled to said propeller for controlling the thrust of the latter in response to flow of pressured fluid through said conduit system, a pump displacement control member, a differential device having its driven element connected to said pump control member for adjusting the latter, said lift rotor thrust control device being coupled to a driving element of said differential, and a pilot-operable directional control member 6 coupled to the other driving element of said differential.

6. In a helicopter aircraft, in combination, a lift rotor, an engine driving said lift rotor, a lift rotor blade pitch change device, a directional control propeller carried by said aircraft and directed laterally thereof to provide thrust forces countering the torque reaction forces transmitted to the aircraft from the lift rotor, a hydraulic power supply system for said propeller comprising a pump driven by said engine and adapted to circulate pressured fluid through a closed circuit conduit system, said conduit system having a motor in series therewith coupled to said propeller and adapted to operate in response to flow of pressured fluid through said conduit system, to control the thrust of said propeller, a pump displacement control member, a differential having its driven element connected to said pump displacement control member and its driving elements connected respectively to said lift rotor blade pitch change device and to a pilot-operable aircraft directional control member.

7. In a helicopter aircraft, in combination, a lift rotor, an engine driving said lift rotor, a power output control for said engine, a pilot-operable lift rotor blade pitch change device, a directional control propeller carried by said aircraft and directed laterally thereof to provide thrust forces countering the torque reaction forces transmitted to the aircraft from the lift rotor, a hydraulic power supply system for said propeller comprising a pump driven by said engine and adapted to circulate pressured fluid through a closed circuit conduit system, said conduit system having a motor in series therewith coupled to said propeller and adapted to operate in response to flow of pressured fluid through said conduit system tocontrol the thrust of said propeller, a pump displacement control member, a differential having its driven element connected to said pump displacement control member and one of its driving elements connected to a pilot-operable aircraft directional control member and the other of its driving elements connected for selective actuation thereby to said engine power control and said lift rotor blade pitch change device.

JOHN C. 'IROTTER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 7 Date 1,472,148 Berliner Oct. 30, 1923 2,318,259 Sikorsky May 4, 1943 1,980,999 Larsen Nov. 20, 1934 2,190,812 Wahlmark Feb. 20, 1940 1,971,734 Stalker Aug. 28, 1934 2,317,340 Bennett Apr. 27, 1943 

